Evaluation of Displacement Demands for Existing RC Buildings Using Spectral Reduction Based on Equivalent Viscous Damping

This study investigates the relationship between spectral reduction and structural demand using different equivalent viscous damping approaches for existing reinforced concrete (RC) buildings. In that regard, 20 existing reinforced concrete buildings ranging from three to seven stories were selected. Equivalent viscous damping ratios were obtained based on the building period and ductility values using Applied Technology Council (ATC) 40 and Priestley et al. approaches. Subsequently, the corresponding spectral reduction factors were computed using various spectral reduction models existing in the literature. These reduction factors were then applied to design spectra defined for different soil classes in Turkish Building Earthquake Code (TBEC) 2018 to estimate the inelastic spectral demands. Finally, a comparison was conducted in terms of the obtained spectral reduction coefficients and spectral demands, highlighting the influence of different damping models on expected structural response.